Implementing Disaster Recovery
1. Understanding RTO and RPO Requirements
| Metric | Definition |
|---|---|
| RTO (Recovery Time Objective) | Max acceptable downtime |
| RPO (Recovery Point Objective) | Max acceptable data loss (time) |
| Tier 1 (critical) | RTO mins, RPO < 1 min |
| Tier 2 | RTO 1-4h, RPO 15-60 min |
| Tier 3 | RTO 24h+, RPO daily |
2. Implementing Backup Strategies
| Type | Detail |
|---|---|
| Full | Complete snapshot |
| Incremental | Changes since last backup |
| Differential | Changes since last full |
| Continuous (WAL) | Stream log → object store |
| 3-2-1 rule | 3 copies, 2 media, 1 offsite |
3. Implementing Cross-Region Backups
| Tool | Detail |
|---|---|
| S3 CRR | Cross-region replication |
| RDS snapshot copy | Cross-region copy |
| GCS multi-region | Built-in geo-redundancy |
| Object Lock / immutability | Ransomware protection |
4. Implementing Disaster Recovery Plans
| Strategy | RTO/RPO | Cost |
|---|---|---|
| Backup & restore | Hours / hours | $ |
| Pilot light | 10s of min / mins | $$ |
| Warm standby | Minutes / mins | $$$ |
| Multi-site active | Sub-min / sec | $$$$ |
5. Implementing Failover and Failback Procedures
| Step | Detail |
|---|---|
| Failover | Promote DR; redirect traffic; freeze old |
| Validate | Smoke tests, data integrity |
| Failback | Sync back to primary; controlled cutover |
| Runbook | Step-by-step; tested regularly |
6. Implementing Data Recovery Procedures
| Type | Detail |
|---|---|
| Full restore | From latest full backup |
| PITR | Restore + replay WAL to specific time |
| Granular | Single table / row from logical backup |
| Verify checksum | Post-restore validation |
7. Testing Disaster Recovery Plans
| Test | Detail |
|---|---|
| Tabletop | Walkthrough scenarios |
| Partial failover | Single component |
| Full DR drill | Switch all traffic to DR |
| GameDay | Inject real failures (Chaos) |
| Cadence | Quarterly minimum for tier 1 |
8. Implementing Point-in-Time Recovery
| DB | Mechanism |
|---|---|
| Postgres | Base backup + WAL archive (pgBackRest, WAL-G) |
| MySQL | Backup + binlog |
| RDS / Aurora | Built-in within retention window |
| DynamoDB | PITR — last 35 days |
9. Understanding Backup Retention Policies
| Tier | Retention |
|---|---|
| Daily | 7-30 days |
| Weekly | 4-12 weeks |
| Monthly | 12 months |
| Yearly | 7+ years (compliance) |
| GFS scheme | Grandfather-Father-Son rotation |
10. Implementing Business Continuity Planning
| Element | Detail |
|---|---|
| BIA | Business Impact Analysis: critical processes, dependencies |
| Roles | Incident commander, comms lead, ops lead |
| Comms plan | Internal + customer + status page |
| Vendor SLAs | Cloud, SaaS dependencies mapped |
| Post-incident review | Blameless retro; action items |